osmocom-sdr January 2022

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6 participants
19 discussions

None
by None 03 Jan '22

03 Jan '22

receive. From those, if the geometry is appropriate (I know the VORs = positions from a database) I can calculate a = position.<o:p></o:p></p></div><div><p = class=3DMsoNormal><o:p> </o:p></p></div><div><p = class=3DMsoNormal>The software then just round-robin tunes the VORs in = range and continually tries to calculate positions. If too many drop = out, it returns to the initial scan mode.<o:p></o:p></p></div><div><p = class=3DMsoNormal><o:p> </o:p></p></div><div><p = class=3DMsoNormal>Not being able to receive this VOR or that VOR is not = generally a problem, but obviously, the more the better. With extra VORs = I have better options for choosing the closest ones or the ones with the = best geometry.<o:p></o:p></p></div><div><p = class=3DMsoNormal><o:p> </o:p></p></div><div><p = class=3DMsoNormal><o:p> </o:p></p></div><div><p = class=3DMsoNormal>This is actually quite difficult to test, because VORs = can generally only be received line-of-sight -- which means in the air. = I'm a private pilot but I found that flying and noodling with a laptop = is too much trouble. From my office window, on a high floor in Oakland, = CA, I can receive one VOR from the Oakland airport. And I have now = discovered a ridge near my home with a scenic overlook from which I can = receive two.<o:p></o:p></p></div><div><p = class=3DMsoNormal><o:p> </o:p></p></div><div><p = class=3DMsoNormal>I've tested the software enough to know that the = initial scan function seems to work, and the morse decoding kind of = works, but I am not confident I'll get it to work very well. (One = transmitter's dit looks a lot like another's dah.) The nav signal = decoding is simple. (A 30 Hz AM modulated tone is phase compared with a = 30 Hz tone FM modulated at 9960 Hz. The phase obtained is the azimuth to = the station.)<o:p></o:p></p></div><div><p = class=3DMsoNormal><o:p> </o:p></p></div><div><p = class=3DMsoNormal><o:p> </o:p></p></div><div><p = class=3DMsoNormal>If I ever get this working, I looking forward to = sharing it with the community. In the process of building this, I = created a simple SDR toolkit of DSP functions. It's like Gnuradio in = concept, but 16b fixed-point, and has no external dependencies, and C89, = so is easier to build on weird and limited platforms. It also has perl = bindings. Compared to GR, it looks like the work of a rank amateur just = learning DSP, but I do like the concept of there being a GR-like library = out there, lightweight and = embedded-friendly.<o:p></o:p></p></div><div><p = class=3DMsoNormal><o:p> </o:p></p></div><div><p = class=3DMsoNormal><o:p> </o:p></p></div><div><p = class=3DMsoNormal>Regards,<o:p></o:p></p></div><div><p = class=3DMsoNormal>Dave J<o:p></o:p></p></div><div><div><div><p = class=3DMsoNormal = style=3D'margin-bottom:12.0pt'><o:p> </o:p></p><div><p = class=3DMsoNormal>On Tue, Oct 22, 2013 at 3:06 AM, jdow <<a = href=3D"mailto:jdow@earthlink.net" = target=3D"_blank">jdow(a)earthlink.net</a>> wrote:<o:p></o:p></p><p = class=3DMsoNormal>He sent me two frequencies in private email. These = were in the FM<br>broadcast band (in the US). He probably needs to notch = them out<br>in order to get adequate response.<br><br>As for wanting = narrow bandwidth - I am not quite sure why he thinks<br>that is a = benefit. I use a large FFT (about 10 Hz per bin) and use<br>the zoom = control to see fine detail. (Different FFT settings suite<br>different = uses. This one seems to be a good compromise with my two<br>needs. I'm = too lazy to change it.)<br><br>{^_^}<o:p></o:p></p><div><div><p = class=3DMsoNormal><br><br><br>On 2013/10/22 02:08, Sylvain Munaut = wrote:<o:p></o:p></p><blockquote style=3D'border:none;border-left:solid = #CCCCCC 1.0pt;padding:0cm 0cm 0cm = 6.0pt;margin-left:4.8pt;margin-right:0cm'><p class=3DMsoNormal>Effective = filtering must occur between antenna and receiver. All the<br>problems = that a saturated preamp and ADC cause can’t be repaired = by<br>software. Never.<o:p></o:p></p></blockquote><p class=3DMsoNormal = style=3D'margin-bottom:12.0pt'><br>But his original problem is not with = saturated preamps or ADC ... it's<br>aliasing ... and that can be solved = in the digital domain provided<br>fast enough = ADC.<br><br>Cheers,<br><br>    = Sylvain<br><br><o:p></o:p></p></div></div></div><p = class=3DMsoNormal><o:p> </o:p></p></div></div></div></div></div><p = class=3DMsoNormal><o:p> </o:p></p></div></div></div></body></html> ------=_NextPart_000_0073_01CF2656.CE93A820--

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03 Jan '22

direct sampling mode, only from signal processing view): If you already have analog signal as separated I&Q in baseband (so called zero-IF), and do I&Q two channel A/D converter, you can processing signal, highest frequency of which is less than sampling rate, without aliasing. That means, for example, you can processing signal, frequency of which is up to 28.8MHz, when sampling rate is 28.8MHz. (There is an implicit assumption that your zero-IF analog channel is ideal) If you have to do sampling on a single channel analog signal( not zero-IF, I&Q not separated by analog circuit, I&Q are still mixed together by an IF carrier/frequency), you have to ensure the highest frequency of signal less than half of sampling rate to ensure no aliasing. On Wed, Jan 29, 2014 at 7:50 AM, Richard Koch <n1gp(a)hotmail.com> wrote: > Can someone clarify what the frequency range is in Direct sampling mode. > > The rtl2832u dongle has a 28.8Mhz osc. > > So can the dongle in "direct sampling mode" (with appropriate antenna > connection) > receive > 14.4 Mhz (Nyquist) ? > > Googling I find conflicting advice. > > I've been able to receive > 14.4 Mhz in direct mode, but I'm not sure if > that's due to some non-optimal method...? > > I'm guessing it can because the tuner chip provides both I & Q data > therefore > allowing the double rate...? > > > > --047d7bf15fc8eed8c404f1137e92 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable <div dir=3D"ltr"><div><div>From the point of view of signal processing (not= very clear about your direct sampling mode, only from signal processing vi= ew):<br></div>If you already have analog signal as separated I&Q in bas= eband (so called zero-IF), and do I&Q two channel A/D converter, you ca= n processing signal, highest frequency of which is less than sampling rate,= without aliasing.<br> </div><div>That means, for example, you can processing signal, frequency of= which is up to 28.8MHz, when sampling rate is 28.8MHz. (There is an implic= it assumption that your zero-IF analog channel is ideal)<br><br></div>If yo= u have to do sampling on a single channel analog signal( not zero-IF, I&amp= ;Q not separated by analog circuit, I&Q are still mixed together by an = IF carrier/frequency), you have to ensure the highest frequency of signal l= ess than half of sampling rate to ensure no aliasing.<br> <br></div><div class=3D"gmail_extra"><br><br><div class=3D"gmail_quote">On = Wed, Jan 29, 2014 at 7:50 AM, Richard Koch <span dir=3D"ltr"><<a href=3D= "mailto:n1gp@hotmail.com" target=3D"_blank">n1gp(a)hotmail.com</a>></span>= wrote:<br> <blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p= x #ccc solid;padding-left:1ex"> <div><div dir=3D"ltr">Can someone clarify what the frequency range is in Di= rect sampling mode.<br><br>The rtl2832u dongle has a 28.8Mhz osc. <br><br>S= o can the dongle in "direct sampling mode" (with appropriate ante= nna connection)<br> receive > 14.4 Mhz (Nyquist) ?<br><br>Googling I find conflicting advice= .<br><br>I've been able to receive > 14.4 Mhz in direct mode, but I&= #39;m not sure if<br>that's due to some non-optimal method...?<br><br> I'm guessing it can because the tuner chip provides both I & Q data= therefore<br>allowing the double rate...?<br><br><br><br> </div= ></div> </blockquote></div><br></div> --047d7bf15fc8eed8c404f1137e92--

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03 Jan '22

VOR from the Oakland airport. And I have now discovered a ridge near my home with a scenic overlook from which I can receive two. I've tested the software enough to know that the initial scan function seems to work, and the morse decoding kind of works, but I am not confident I'll get it to work very well. (One transmitter's dit looks a lot like another's dah.) The nav signal decoding is simple. (A 30 Hz AM modulated tone is phase compared with a 30 Hz tone FM modulated at 9960 Hz. The phase obtained is the azimuth to the station.) If I ever get this working, I looking forward to sharing it with the community. In the process of building this, I created a simple SDR toolkit of DSP functions. It's like Gnuradio in concept, but 16b fixed-point, and has no external dependencies, and C89, so is easier to build on weird and limited platforms. It also has perl bindings. Compared to GR, it looks like the work of a rank amateur just learning DSP, but I do like the concept of there being a GR-like library out there, lightweight and embedded-friendly. Regards, Dave J On Tue, Oct 22, 2013 at 3:06 AM, jdow <jdow(a)earthlink.net> wrote: > He sent me two frequencies in private email. These were in the FM > broadcast band (in the US). He probably needs to notch them out > in order to get adequate response. > > As for wanting narrow bandwidth - I am not quite sure why he thinks > that is a benefit. I use a large FFT (about 10 Hz per bin) and use > the zoom control to see fine detail. (Different FFT settings suite > different uses. This one seems to be a good compromise with my two > needs. I'm too lazy to change it.) > > {^_^} > > > > On 2013/10/22 02:08, Sylvain Munaut wrote: > >> Effective filtering must occur between antenna and receiver. All the >>> problems that a saturated preamp and ADC cause can=92t be repaired by >>> software. Never. >>> >> >> But his original problem is not with saturated preamps or ADC ... it's >> aliasing ... and that can be solved in the digital domain provided >> fast enough ADC. >> >> Cheers, >> >> Sylvain >> >> >> --089e01184768dfc65f04e955c0d5 Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: quoted-printable <div dir=3D"ltr">I originally posted about 115.8 and 116.8 MHz, both square= in the VOR band of 108 to 117.95. I might have sent something else in a PM= , but if so it was a typo. :-) I am definitely only interested in the VOR b= and right now -- though, as you say, it is adjacent to commercial FM with i= ts high power.<div> <br></div><div>My application is simple in concept: A fully auomatic VOR-ba= sed positioning system, a fallback from GPS. I want to scan the entire VOR = band, looking for signals in the standard VOR format that can be demodulate= d. I do the initial scan with a fast sample rate and FFT, just looking for = peaks. From those, I examine the signals to see if it looks like a VOR sign= al. From that list, I will "park" on each signal long enough (~30= s) to decode the VOR's morse code station ID. From that, I will have a = short list of VORs that I can currently receive. From those, if the geometr= y is appropriate (I know the VORs positions from a database) I can calculat= e a position.</div> <div><br></div><div>The software then just round-robin tunes the VORs in ra= nge and continually tries to calculate positions. If too many drop out, it = returns to the initial scan mode.</div><div><br></div><div>Not being able t= o receive this VOR or that VOR is not generally a problem, but obviously, t= he more the better. With extra VORs I have better options for choosing the = closest ones or the ones with the best geometry.</div> <div><br></div><div><br></div><div>This is actually quite difficult to test= , because VORs can generally only be received line-of-sight -- which means = in the air. I'm a private pilot but I found that flying and noodling wi= th a laptop is too much trouble. From my office window, on a high floor in = Oakland, CA, I can receive one VOR from the Oakland airport. And I have now= discovered a ridge near my home with a scenic overlook from which I can re= ceive two.</div> <div><br></div><div>I've tested the software enough to know that the in= itial scan function seems to work, and the morse decoding kind of works, bu= t I am not confident I'll get it to work very well. (One transmitter&#3= 9;s dit looks a lot like another's dah.) The nav signal decoding is sim= ple. (A 30 Hz AM modulated tone is phase compared with a 30 Hz tone FM modu= lated at 9960 Hz. The phase obtained is the azimuth to the station.)</div> <div><br></div><div><br></div><div class=3D"gmail_extra">If I ever get this= working, I looking forward to sharing it with the community. In the proces= s of building this, I created a simple SDR toolkit of DSP functions. It&#39= ;s like Gnuradio in concept, but 16b fixed-point, and has no external depen= dencies, and C89, so is easier to build on weird and limited platforms. It = also has perl bindings. Compared to GR, it looks like the work of a rank am= ateur just learning DSP, but I do like the concept of there being a GR-like= library out there, lightweight and embedded-friendly.</div> <div class=3D"gmail_extra"><br></div><div class=3D"gmail_extra"><br></div><= div class=3D"gmail_extra">Regards,</div><div class=3D"gmail_extra">Dave J</= div><div class=3D"gmail_extra"><br><br><div class=3D"gmail_quote">On Tue, O= ct 22, 2013 at 3:06 AM, jdow <span dir=3D"ltr"><<a href=3D"mailto:jdow@e= arthlink.net" target=3D"_blank">jdow(a)earthlink.net</a>></span> wrote:<br= > <blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p= x #ccc solid;padding-left:1ex">He sent me two frequencies in private email.= These were in the FM<br> broadcast band (in the US). He probably needs to notch them out<br> in order to get adequate response.<br> <br> As for wanting narrow bandwidth - I am not quite sure why he thinks<br> that is a benefit. I use a large FFT (about 10 Hz per bin) and use<br> the zoom control to see fine detail. (Different FFT settings suite<br> different uses. This one seems to be a good compromise with my two<br> needs. I'm too lazy to change it.)<br> <br> {^_^}<div class=3D"HOEnZb"><div class=3D"h5"><br> <br> <br> On 2013/10/22 02:08, Sylvain Munaut wrote:<br> <blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p= x #ccc solid;padding-left:1ex"><blockquote class=3D"gmail_quote" style=3D"m= argin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> Effective filtering must occur between antenna and receiver. All the<br> problems that a saturated preamp and ADC cause can=92t be repaired by<br> software. Never.<br> </blockquote> <br> But his original problem is not with saturated preamps or ADC ... it's<= br> aliasing ... and that can be solved in the digital domain provided<br> fast enough ADC.<br> <br> Cheers,<br> <br> =A0 =A0 Sylvain<br> <br> <br> </blockquote> </div></div></blockquote></div><br></div></div> --089e01184768dfc65f04e955c0d5--

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it was a saturation issue in RF, it would show up no matter what the sample rate is. Also : - RF filter are often only band specific and not channel specific (because tunable RF filters to do channel selection would be prohibitively expensive) - IF filter (or BB filters for zero-if) are then used for channel selection. So in his case being two channel in the same band (and given the architecture of the dongles), the only saturation that IF filters would provide would be against ADC saturation and it's easy to check if this happens or not just looking at the time domain signal. Cheers, Sylvain

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developer doesn't really know or care about corner cases and as a result it's possible for the GUI to show "green" when in fact there is actually a problem that could be detected. That said, if you've used zadig to install the driver then it should indeed work. > but I can confidently say, I've followed every instruction quite > precisely... I've tried installing the winusb stub for both > instance 0 and 1 What do you mean by instance here again? Sorry if you already mentioned that. If the device has multiple interfaces (a so-called composite device) it is important to install WinUSB for the actual device, and not for either of the two interfaces. > trying everything in both cases in the event that installing it on > the second instance is itself a problem. there's something quite > subtle wrong, given that sdrsharp works perfectly... I don't know how your .exe files were built and if they are using libusb or the hostile fork libusbx which clobbers the soname and uses the same API namespace, the latter driven by that same zadig/libwdi developer. I know the actual libusb very well and it would be interesting to see output from a debug build of my current working directory with libusb source. I've built a binary using the MS C compiler here: http://stuge.se/libusb-1.0.dll Try putting this in the same directory as the program and see if you still have the same problem. Even if the program was built using MinGW that DLL should work well. If yes, the output from the program would be interesting. Thanks //Peter

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ioctl(5, USBDEVFS_CLAIMINTERFACE, 0x7fd063c4) = -1 ENOENT (No such file or directory) The kernel is saying that the interface doesn't exist. lsusb -v for this device run on the fritzbox would be interesting. //Peter

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03 Jan '22

3.54 GHz. The actual mixer frequency sent to the IF stage is the VCO frequency divided by a number between 2 and 63 -- so the possible center frequency tuning range ends up being in the range of ~24 MHz to 1.77 GHz. However, I was wondering if it would be possible to use a MixDiv of 1 -- to run the mixer frequency directly on the VCO? Has anyone tried that, or would it fry the device somehow? Just wondering if the range could be extended (disregarding any sensitivity issues, of course). -- Per.

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r feature of the device won't be of much use to me, but as for the FM, = I'm on the Ubuntu/Linux GNU platform, so I'm awaiting on the kindne= ss of strangers to perfect the kernel drivers enough to match the Windows k= it performance. But that's okay, because I'm learning a lot in the = process :)<br> <br><div class=3D"gmail_quote">On Mon, Aug 13, 2012 at 11:44 PM, Adam Niels= en <span dir=3D"ltr"><<a href=3D"mailto:a.nielsen@shikadi.net" target=3D= "_blank">a.nielsen(a)shikadi.net</a>></span> wrote:<br><blockquote class= =3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padd= ing-left:1ex"> <blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p= x #ccc solid;padding-left:1ex"> so it is /designed/ for FM? =A0That's encouraging because mostly that i= s all I<div class=3D"im"><br> really need from it, only all my experiments so far have yielded only<br></= div> AM-quality sound, but it's good to hear because it means there's /h= ope/ and so<div class=3D"im"><br> I'll just keep hanging in there until an FM recipe surfaces :)<br> </div></blockquote> <br> Yes, because the dongles provide digital TV (via hardware) and as an extra = selling point, analogue FM radio (provided via the SDR.)<br> <br> I don't know what platform you're on or what your goals are, but I = hear the SDR# program for Windows offers excellent stereo FM support, as it= 's one of the few programs that can deal with the ~120kHz bandwidth nee= ded for a WBFM signal.<br> <br> Cheers,<br> Adam.<br> <br> <br> </blockquote></div><br><br clear=3D"all"><div><br></div>-- <br><div style= =3D"text-align:right"><i><span style=3D"font-size:x-small">Have Blog, Will = Travel: </span><span style=3D"font-size:x-small"><a href=3D"http://blog.tel= edyn.com" target=3D"_blank">blog.teledyn.com</a></span></i></div> <div style=3D"text-align:right"><i><span style=3D"font-size:x-small">A Serv= iceable Substitute: <a href=3D"http://post.teledyn.com" target=3D"_blank">p= ost.teledyn.com</a></span></i></div><br> --f46d042fd93a1d197104c738bd48--

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from DVB-T (I am a complete neophyte at all of this) and so that particular feature of the device won't be of much use to me, but as for the FM, I'm on the Ubuntu/Linux GNU platform, so I'm awaiting on the kindness of strangers to perfect the kernel drivers enough to match the Windows kit performance. But that's okay, because I'm learning a lot in the process :) On Mon, Aug 13, 2012 at 11:44 PM, Adam Nielsen <a.nielsen(a)shikadi.net>wrote: > so it is /designed/ for FM? That's encouraging because mostly that is all >> I >> >> really need from it, only all my experiments so far have yielded only >> AM-quality sound, but it's good to hear because it means there's /hope/ >> and so >> >> I'll just keep hanging in there until an FM recipe surfaces :) >> > > Yes, because the dongles provide digital TV (via hardware) and as an extra > selling point, analogue FM radio (provided via the SDR.) > > I don't know what platform you're on or what your goals are, but I hear > the SDR# program for Windows offers excellent stereo FM support, as it's > one of the few programs that can deal with the ~120kHz bandwidth needed for > a WBFM signal. > > Cheers, > Adam. > > > -- *Have Blog, Will Travel: blog.teledyn.com* *A Serviceable Substitute: post.teledyn.com* --f46d042fd93a1d197104c738bd48 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable

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osmocom-sdr January 2022